const WOW_SPECIALIZATIONS = Object.freeze([
  ["warrior:arms", "damage"], ["warrior:fury", "damage"], ["warrior:protection", "tank"],
  ["paladin:holy", "healer"], ["paladin:protection", "tank"], ["paladin:retribution", "damage"],
  ["hunter:beast-mastery", "damage"], ["hunter:marksmanship", "damage"], ["hunter:survival", "damage"],
  ["rogue:assassination", "damage"], ["rogue:combat", "damage"], ["rogue:subtlety", "damage"],
  ["priest:discipline", "healer"], ["priest:holy", "healer"], ["priest:shadow", "damage"],
  ["death-knight:blood", "tank"], ["death-knight:frost", "damage"], ["death-knight:unholy", "damage"],
  ["shaman:elemental", "damage"], ["shaman:enhancement", "damage"], ["shaman:restoration", "healer"],
  ["mage:arcane", "damage"], ["mage:fire", "damage"], ["mage:frost", "damage"],
  ["warlock:affliction", "damage"], ["warlock:demonology", "damage"], ["warlock:destruction", "damage"],
  ["druid:balance", "damage"], ["druid:feral-bear", "tank"], ["druid:feral-cat", "damage"], ["druid:restoration", "healer"],
]);

const READY_IDS = new Set([
  "warrior:protection",
  "priest:discipline",
  "hunter:marksmanship",
  "mage:fire",
  "rogue:assassination",
]);
const SPECIALIZATION_ROLE = new Map(WOW_SPECIALIZATIONS);
const VALID_STATUSES = new Set(["ready", "beta", "needs-testing"]);

export const DEFAULT_COMPANION_SPEC_READINESS_POLICY = Object.freeze({
  schemaVersion: 1,
  statuses: Object.freeze(Object.fromEntries(WOW_SPECIALIZATIONS.map(([id]) => [
    id,
    READY_IDS.has(id) ? "ready" : "needs-testing",
  ]))),
});

function invalid(message) {
  const error = new Error(message);
  error.code = "invalid_companion_spec_readiness";
  return error;
}

export function normalizeCompanionSpecReadinessPolicy(value) {
  if (!value || typeof value !== "object" || Array.isArray(value) || value.schemaVersion !== 1) {
    throw invalid("Companion readiness policy schemaVersion must be 1.");
  }
  if (!value.statuses || typeof value.statuses !== "object" || Array.isArray(value.statuses)) {
    throw invalid("Companion readiness statuses are required.");
  }
  for (const [id, status] of Object.entries(value.statuses)) {
    if (!SPECIALIZATION_ROLE.has(id)) throw invalid(`Unknown WoW specialization: ${id}.`);
    if (!VALID_STATUSES.has(status)) throw invalid(`Invalid readiness status for ${id}.`);
  }
  const statuses = Object.fromEntries(WOW_SPECIALIZATIONS.map(([id]) => [id, value.statuses[id] ?? "needs-testing"]));
  const ready = WOW_SPECIALIZATIONS.filter(([id]) => statuses[id] === "ready");
  if (!ready.some(([, role]) => role === "tank")) throw invalid("At least one tank specialization must be Ready.");
  if (!ready.some(([, role]) => role === "healer")) throw invalid("At least one healer specialization must be Ready.");
  if (ready.filter(([, role]) => role === "damage").length < 3) {
    throw invalid("At least three distinct damage specializations must be Ready.");
  }
  return { schemaVersion: 1, statuses };
}

export function cloneDefaultCompanionSpecReadinessPolicy() {
  return JSON.parse(JSON.stringify(DEFAULT_COMPANION_SPEC_READINESS_POLICY));
}